The completion method is as follows:

1. Go to the park: Take the character to the park map in the game.

2. Find the sound equipment: Find the sound equipment in the park. It will appear in the form of a large sound station that can be searched in different areas of the park.

3. Interactive operation: Click on the audio device to interact with it. To select the "Turn on the speakers" option.

4. Random music: In the audio interface, find and select the "Random Music" option. This will cause the speaker to play a random piece of music.

5. Invite other characters to participate: In the task requirements, other characters must be invited to join the Rhythm Master activity. You can interact with other characters by selecting the "Invite to the Rhythm Master Event" option.

6. Complete the task: When other characters are successfully invited to participate in the Rhythm Master event, the task will be marked as completed.